1. Field of the Invention
The present invention relates to an organic electroluminescence device, and more particularly, to an organic electroluminescence device with improved interfacial adhesion between a substrate and a sealant.
2. Description of the Related Art
Organic electroluminescence devices are deteriorated by moisture. Thus, a passivation structure for preventing moisture permeation is required.
In a conventional sealing structure, a metal can or a glass plate is processed into a cap having grooves, and a moisture-absorbing desiccant in powder form is loaded into the grooves. Alternatively, a film type desiccant is attached using a double-sided tape.
However, the method of loading the desiccant in powder form into the grooves is complicated and raises costs. In addition, the overall thickness of a substrate becomes thick, and the substrate used for passivation is not transparent so that it cannot be used for front emission. A metal can used for passivation is structurally rigid, whereas an etched glass is structurally fragile and is easily damaged by external impacts. When passivation is achieved using the film type desiccant, the permeation of moisture cannot be completely prevented, and the structure is likely to be broken by external impacts in a manufacturing process or in use. Therefore, passivation using the desiccant film is not suitable for mass production due to poor durability and low reliability.
Japanese Patent Laid-open Publication No. hei 9-148066 discloses an organic electroluminescence display device including a stacked structure with an organic emissive material layer interposed between a pair of opposing electrodes, a container sealing the stacked structure, and a desiccant such as an alkali metal compound placed inside the container. However, the organic electroluminescence display device is considerably thick due to the structure of the sealing container. In addition, even though the desiccant remains in a solid state after absorbing moisture, it is opaque and unsuitable for a front emission organic electroluminescence device. In addition, as described above, expensive materials and the complicated manufacturing processes increase the overall costs.
With development of a transparent, moisture-absorbing encapsulating layer for front emission organic electroluminescence devices, processing techniques relevant to the transparent encapsulating layer are being considered to be important. Among currently available transparent, moisture-absorbing encapsulating layer manufacturing techniques, a method of filling a glass cap with a liquid transparent moisture-absorbing material and calcinating it to form a coated layer is commonly used.
However, according to the conventional method, circumferential contamination occurs when coating the transparent moisture-absorbing material, and outgassing from solvents occurs during the calcinating process. As a result, the interfacial adhesion between the sealant and the glass substrate greatly decreases, thereby fatally affecting the lifetime characteristics of the device.